# system.opc.readValue config error **URL:** \ **Category:** Ignition\ **Created:** [May 20, 2020, 4:56pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916 "2020-05-20T16:56:44Z")\ **Posts on this page:** 18\ **Page:** 2
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [May 23, 2020, 1:13pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/21 "2020-05-23T13:13:37Z")
I don’t know then. Make sure Ignition is actually running, its own loopback connection works, and check the bind address you have configured for the server. ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [May 23, 2020, 1:19pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/22 "2020-05-23T13:19:04Z")
Loopback connection to ignition is enabled. However anonymous access was disabled, I enabled it and saved the changes and tried again but still it gives same error. I don't know what is "User Source", it is set to opcua-module, i tried changing it to Default, but same error. Do I have to restart the Ignition server? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [May 23, 2020, 1:19pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/23 "2020-05-23T13:19:45Z")
You have to restart for anonymous access to be allowed, but that’s not likely to fix the error you’re seeing. Don’t change the user source or you’ll break your loopback connection. ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [May 23, 2020, 1:20pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/24 "2020-05-23T13:20:52Z")
hmmm.... let me do some more trial and error. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [May 23, 2020, 1:22pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/25 "2020-05-23T13:22:12Z")
Take a screenshot of your Config \> OPC UA \> Server Settings page. ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [May 23, 2020, 1:23pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/26 "2020-05-23T13:23:16Z")
![image](https://us1.discourse-cdn.com/inductiveautomation/original/2X/8/8521475113cba5b5c08644b0bc9e82e6b74d9ce2.png) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [May 23, 2020, 1:26pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/27 "2020-05-23T13:26:59Z")
Seems fine, but you’ll eventually need to change your Security Policies to “None,Basic256Sha256” and restart again once you figure out this socket/network error, or the Python client won’t be able to connect. ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [May 23, 2020, 1:27pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/28 "2020-05-23T13:27:55Z")
Thanks a lot , i will try after a while and update you... ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [May 23, 2020, 4:04pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/29 "2020-05-23T16:04:11Z")
I changed the security policy to None and saved the settings, but the same error. Do I need to restart to gateway server or OPC server? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [May 23, 2020, 4:10pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/30 "2020-05-23T16:10:35Z")
Any change in that settings area requires a restart of the OPC UA module or gateway. ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [May 23, 2020, 4:15pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/31 "2020-05-23T16:15:45Z")
Yes, I restarted the module and I think it connected! However it gives the warning `Requested session timeout to be 3600000ms, got 120000ms instead` So guess its a very basic client without any encryption ! I will just test if I am able to browse the server , that will confirm if its working! ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [May 23, 2020, 4:42pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/32 "2020-05-23T16:42:43Z")
Yes, its working fine, the command objects.get\_children() gives: `[Node(FourByteNodeId(i=2253)), Node(StringNodeId(ns=1;s=Devices)), Node(StringNodeId(ns=2;s=Tag Providers))]` It seems to be working fine. I need to test teh remaining functions. Thanks a lot Kevin! ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [June 3, 2020, 5:15am UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/33 "2020-06-03T05:15:51Z")
What is the information model used in OPC UA server of Ignition? i.e. Structure of the nodes and references and reference types , name spaces etc? Any write up available? Some guidance will be appreciated. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [June 3, 2020, 12:03pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/34 "2020-06-03T12:03:05Z")
Other than the nodes belonging to namespace 0 there is no defined information model. There’s a Devices folder referenced by the Objects folder. Each device instance is represented by its own folder under the Devices folder. Nodes are just BaseDataVariableNodes. Most references are either Organizes or HasComponent. There are no custom ObjectTypes, VariableTypes, DataTypes, or References. ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [June 5, 2020, 3:55pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/35 "2020-06-05T15:55:00Z")
Does Ignition OPC UA server support Pub/Sub specs? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [June 5, 2020, 3:56pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/36 "2020-06-05T15:56:38Z")
No, Ignition’s OPC UA implementation is for version 1.03 of the spec. PubSub is from 1.04. I don’t know if we’ll implement it even when we get basic 1.04 support. ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [June 6, 2020, 10:15am UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/37 "2020-06-06T10:15:55Z")
Also I guess same will be the case with AE and HA modules of OPC? As it doesn't make sense to revamp the already excellently working Alarms and History modules of Ignition? ---
**Author:** ![PRAMANJ](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pramanj/32/66935_2.png) [@PRAMANJ](https://forum.inductiveautomation.com/u/PRAMANJ)\ **Post date:** [June 15, 2020, 1:58pm UTC](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916/38 "2020-06-15T13:58:15Z")
How are arrays and UDT Tags exposed in OPC when tag providers are exposed? Are arrays mapped as appropriate array type in OPC? Are each UDT columns exposed as arrays or individual tags?(sorry I am asking without trying it out myself, just to save some time for myself). [Previous page](https://forum.inductiveautomation.com/t/system-opc-readvalue-config-error/34916.md?page=1)